Curious about Spike Launcher Perk "Exit Wounds."

ϻihm

So in the 5 days of playing on DoomSpear I found myself at level 50 spike launcher and picked the perk "Exit Wounds." The perk says "Spike launcher hits cause your target to Bleed 0.5% of their missing HP for two seconds." I'm confused about the entirety of the perk, I've tried using it without poison to check it's damage since there isn't a secondary damage color and only weapon/poison white DPS numbers. While using no poisons I see zero damage coming from this skill even watching the HP bar and firing a full clip instantly ( 9 spikes as of my weapon with Hail Of Spikes) and it doesn't tick down any health of any of the targets I've hit. So my questions are: Does this skill even work, and if it does, Is each spike 100% going to wound the target in PVE with no wound res?I've done a little bit of bad math so could be wrong but if I shot 9 spikes instantly with the level 25 perk wouldn't I be doing 4.5% bleeding ticks minimum and definitely see the HP bar lowering? Also the bleed ticks twice one for each second so I should clearly see big drops in their HP bars these skills go hands and hand since it literally shoots your entire clip at once. https://prnt.sc/lpwjf2

ϻihm

Or is the damage just adding multiple dots of 0.5% damage for each bullet? These perks just don't go in enough detail to be honest this skill may be the worst skill I've tried to figure out, I've edited this post multiple times just racking my brain over how this damage would be calculated and can't fathom why it does literally no damage. I'm just going off it applies multiple dots of 0.5% damage instead of doing increased 4.5% when proct off hail of spikes (9 bolts fired all at once instantly.) I'm also assuming it doesn't work with hail of spikes at all and if it does the damage is so low you can't even see it doing anything at all.